236 AFFECTION OF INSECTS FOR THEIR YOUNG. 



alternately ; and, while their vertical effect is that of a saw, act laterally 

 as a rasp. When by this alternate motion the incision, or cell, is made, 

 the two saws, receding from each other, conduct the egg between them 

 into it.^ The Cicada, so celebrated by the poets of antiquity, which lays 

 its eggs in dry wood, requires a stronger instrument of a different con- 

 struction. Accordingly it is provided with an excellent double anger, the 

 sides of which play alternately and parallel to each other, and bore a 

 hole of the requisite depth in very hard substances without ever being 

 displaced.^ 



The construction of the sting or ovipositor with which the different 

 species of Ichneumon are provided, is not less nicely adapted to its various 

 purposes. In those which lay their eggs in the bodies of caterpillars that 

 feed exposed on the leaves of plants it is short, often in very large species 

 not the eighth of an inch long: having free access to their victims, a 

 longer sting would have been useless. But a considerable number oviposit 

 in larvae which lie concealed where so short an instrument could not pos- 

 sibly approach them. In these, therefore, the sting is proportionably 

 elongated, so much so that in some small species it is three or four times 

 the length of the body. Thus in Pimpla Manifestator, whose economy 

 has been so pleasingly illustrated by Mr. Marsham^, and which attacks 

 the larva of a wild bee (^Chelostoma'^ maxillosa) lying at the bottom of 

 deep holes in old wood, the sting is nearly two inches long : and it is not 

 much shorter in the more minute /. Strobilellce L., which lays its eggs in 

 larvae concealed in the interior of fir cones, which without such an appa- 

 ratus it would never be able to reach. 



The tail of the females of many moths whose eggs require to be 

 protected from too severe a cold and too strong a light, is furnished, evi- 

 dently for application to this very purpose, with a thick tuft of hair. But 

 how shall the moth detach this non-conducting material and arrange it 

 upon her eggs? Her ovipositor is provided at the end with an instrument 

 resembling a pair of pincers, which for this purpose are as good as hands. 

 With these, having previously deposited her eggs upon a leaf, she pulls off 

 her tuft of hairs, with which she so closely envelops them as effectually 

 to preserve them of the required temperature, and having performed this 

 last duty to her progeny she expires. 



The ovipositor of the Capricorn beetles, an infinite host, is a flattened 

 retractile tube, of a hard substance, by means of which it can introduce 

 its eggs under the bark of timber, and so place them where Its progeny 

 will find their appropriate food.^ The auger used by certain species of 

 CEstrus, to enable them to penetrate the hides of oxen or deer and form 

 a nidus for their eggs, has been before described. — But to enumerate all 

 the varieties of these instruments would be endless. 



The purpose which in the insects above mentioned is answered by their 

 anal apparatus is fulfilled in the numerous tribes of weevils by the long 



1 Prof. Peck's Nat. Hist, of the Slug-ivorm, t. 12. f, 12—14. 



* Dr. Burmeister and M Doyere consider the central piece of the borer of the Cicada as 

 the really piercing organ, and the lateral files as only serving as a point of support ; but 

 Mr. Westwood states that numerous dissections of these parts have convinced him of the 

 correctness of Reaumur's description, that the lateral serrated pieces are the real organs of 

 perforation. {Mod. Clnssif. of Ins. ii. 424.) 



3 Linn. Trans, iii. 23. * Apis.**, c. 2. y. K. 



* See Kirby ia Linn. Trans, v. 254. t. 12. f. 15. 



